Effect of Exit Shape of Submerged Entry Nozzle on Flow Field and Slag Entrainment in Continuous Casting Mold
- PDF / 3,832,495 Bytes
- 9 Pages / 593.972 x 792 pts Page_size
- 86 Downloads / 219 Views
RODUCTION
THE submerged entry nozzle (SEN) decisively affects fluid flow within a continuous casting mold and is used to improve the quality of a steel strand. The functions of the SEN include preventing the spatter and secondary oxidation of molten steel, improving the distributions of temperature and the flow fluid, and promoting the floatation of inclusions. Reasonable combinations of SEN structural parameters, such as the inner diameter, shape of the nozzle, inclination angle, and number of exits, are useful in developing various measures and strategies to control strand quality.[1,2] In recent years, to improve the process efficiency and design control operation conditions of lower cost, mathematical and physical models have become reliable options in conducting in-depth studies in the field of metallurgy. The effect of design parameters and
MEIJUAN GAN, WEIJIE PAN, QIANGQIANG WANG, XUBIN ZHANG, and SHENGPING HE are with the College of Materials Science and Engineering, and Chongqing Key Laboratory of Vanadium-Titanium Metallurgy and Advanced Materials, Chongqing University, Chongqing 400044, China. Contact e-mail: [email protected] Manuscript submitted July 9, 2020; accepted September 24, 2020.
METALLURGICAL AND MATERIALS TRANSACTIONS B
operation conditions of the nozzle on the flow behaviors of liquid steel in a mold have been investigated.[3–7] Naijat [8] studied turbulence flow and found that, for a bifurcated nozzle with a square or rectangular exit and inclination of 25 deg, the full occupation of the exit zone by molten steel best prevented the adherence of inclusions on the wall surface. Bai[9] demonstrated that a nozzle with a square exit had a higher jet speed and allowed stronger swirl near the exit region, leading to asymmetrical flow within the mold, compared with a nozzle having a rectangular exit. Ismael[10] determined the relationship between the nozzle exit shape and the stability of the flow jet to characterize fluid flow turbulence in a mold. These studies indicated that the shape of the nozzle exit appreciably affects the flow field in a mold and the deposition of inclusions on the nozzle wall. The current authors observed an interesting phenomenon in their investigation of the relationship between the strand quality of low-carbon Al-killed steel and process parameters at a steel plant. Under the condition that the cleanliness of molten steel and other casting parameters remained the same, the nozzle with an approximately oval exit maintained a smooth inner wall with few deposits at the end of sequence casting; the subsequent defect rates relating to slag entrainment were 1 and 1.2 pct for hot-rolled and cold-rolled plates, respectively.
Approximately oval and rectangular nozzle exit shapes are shown in Figure 1. All above three aspects performed much better than cases using a nozzle with rectangular exit; details are listed in Table I. For ease of description, the present paper uses N-AO and N-R in place of the nozzles with an approximately oval exit and rectangular exit, respectively. Intuitively, as the
Data Loading...
